HD74HC390 Datasheet, PDF (1/9 Pages) Hitachi Semiconductor – Dual Decade Counters

HD74HC390
Dual Decade Counters
Description
The HD74HC390 incorporate dual decade counters, each composed of a divide-by-two and a divide-by-
five counter. The divide-by-two and divide-by-five counters can be cascaded to form dual decade, dual bi-
quinary, or various combinations up to a single divide-by-100 counter.
The HD74HC390 is incremented on the high to low transition (negative edge) of the clock input, and each
has an independent clear input. When clear is set high all four bits of each counter are set to a low level.
This enables count truncation and allows the implementation of divide-by-N counter configurations.
Features
• High Speed Operation: t_pd (Clock A to Q_A) = 11 ns typ (C_L = 50 pF)
• High Output Current: Fanout of 10 LSTTL Loads
• Wide Operating Voltage: V_CC = 2 to 6 V
• Low Input Current: 1 µA max
• Low Quiescent Supply Current: I_CC (static) = 4 µA max (Ta = 25°C)
Function Table
Clock
A
B
X
X
X
X
Clear
H
L
L
Operation
Clear ÷2 and ÷5
Increment ÷2
Increment ÷5